Wax bite rim former



MarCh 25, 1947. I p EN 2,417,812

WAX BITE RIM FORMER Filed Aug. 20, 1945 FIG. 3

PAUL GORDON GURREN WWLW -W Patented Mar. 25,1947

UNITED STATES PATENT OFFICE 3 Claims.

This invention relates to molds for casting plastic materials and particularly to a separable mold adapted for use in forming wax bite rims in the making of artificial dentures.

Prior to this invention, it was customary to form wax bite rims from dental base plate wax in sheet form by pressing warmed sheets together and then shaping to the general curvature of the base plate. Such wax bite rims were subject to many disadvantages, such as delamination or other failure during manipulation and especially during the forming of a groove to receive the grinding mixture of artificial stone and carborundum grit.

It is an object of this invention to provide a simple and efiicient mold for casting wax bite rims from molten wax.

It is a further object of this invention to provide a simple mold in two sections to facilitate the removal of the wax bite rims.

Another object of the invention is to provide means for removably securing the two sections of the mold and permitting ready separation of the sections for the removal of the formed material.

With these and other objects in view the invention consists in the combination and arrangement of parts as set forth in the claims and illustrated in the drawing, wherein Fig. 1 is a plan view in perspective of one embodiment of my invention, showing the two sections of the mold in assembled position;

Fig. 2 is a plan view of a bite rim; and

Fig. 3 is a sectional view of the bite rim.

Referring more specifically to Fig. 1 of the drawing, an embodiment of my invention is illustrated comprising three pieces of strap material, such as strap steel having a width of about three quarters of an inch. The mold is a two-section mold, the outer section consisting of two pieces of strap metal, secured together by rivetting or the like, and the inner section consisting of one piece of strap metal with the two ends secured by rivetting or the like.

The numeral Ill indicates a U-shaped member of strap metal, forming the concave wall of the mold, and having rolled ends H and I2. Overlying the U-shaped member ID is a similar member 13, rigidly secured to member H], such as by means of rivets l4 and I5, which may be countersunk to provide a smooth mold surface. The end portions of member I3 are curved outwardly and then inwardly to form arcuate, spring-biased clips l6 and H, the ends of which are adjacent the ends II and I2, respectively, of the concave wall-forming member to. Thus, a slot is formed amended April 30, 1928; 370 0. G. 757) 2 to receive tongue-like projections of the. inner mold member hereinafter described, and the spring-biased clips l6 and IT resiliently secure these tongue-like projections.

The inner member of the mold is made up of a U-shaped, convex portion i8 and oppositely and laterally extending, clip-engaging portions i9 and 2'6. The convex portion [8 is complementary to concave portion l0 and spaced therefrom to form a mold recess 2| to receive the plastic material to be molded in the form of a dental bite rim. The mold recess 2! has a rectangular cross section of substantially the same dimensions at all points. Clip-engaging portions l9 and 20 are provided with depressions or grooves on each side thereof to receive the rounded ends I! and 12 of the outer mold member In on one side, and the rounded ends of spring-biased clips l6 and ll on the other side. In this manner, two tongue and groove joints are formed which hold the two sections of the mold together securely. The mold can be separated by sliding the two sections apart in the direction of the grooves,

. or the clips i6 and H may be disengaged by artificial dentures.

springing outwardly to permit the inner section of the mold to be pulled away from the molded material.

The base portion 22 serves as a spacing member and provides reenforcement for the assembled mold. As shown in the drawing, portions [8, I9, 20 and 22 are formed of a single piece of strap material, joined such as by rivet 23, the single piece being bent upon itself to form a central convex portion and oppositely extending clip en-. gaging means.

In utilizing my novel mold for forming dental bite rims, the two sections of the mold are assembled and placed on a smooth surface, such as a glass slab. The mold surfaces and the glass slab are provided with a thin coating of any suitable separating medium, such as petrolatum or the like. The mold recess 2| is then filled with a suitable plastic material for forming the bite rim, preferably, molten dental base plate wax. After cooling until the wax is firm enough tobe handled, the mold and its contents are placed in cold water to completely solidify the wax, the mold is separated, and the wax bite rim removed.

In the cooling process, the upper surface of the bite rim contracts, forming a concave depression 25, Figs. 2 and 3, which is adapted to fit over the ridge area of a base plate.

The resulting wax bite rim may be used in the conventional manner in the process of making For example, the bite rim may be fitted over the ridge area of a composition base plate, waxed thereto with a hot spatula, trimmed as desired, and smoothed. A groove may then be formed in the upper surface of the bite rim to receive a grinding mixture, such as plaster of Paris and carborundum grit.

While the invention has been described with reference to the specific arrangement shown, it is not limited to the details of construction disclosed, and it is intended to cover such modifications as may come within the, purposes of the improvement and the scope of the appended claims.

The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

' I claim:

1. A two-section, separable, dental mold for forming wax bite rims which comprises an outer U-shaped section of strap material, a complementary inner section of strap material having a U-shaped central portion and laterally extending clip-engaging means, said two sections defining an arcuate mold recess, and a pair of clips attached to said outer section forming slots with the ends of said outer section to receive said clipengaging means.

2. A two-section, separable, dental mold for forming bite rims from molten wax which comprises an outer U-shaped section of strap material, a complementary inner section having a 4 U-shaped central portion and laterally extending clip-engaging means, said two sections defining a gum-shaped recess to receive molten wax, and a pair of clips attached to said outer section, curving outwardly to provide space for the ends of said clip-engaging means, the ends of said clips being in opposed relation to the ends of said outer section, to provide slots to receive said clipengaging means.

3. A two-section, separable, dental mold for forming bite rims from molten wax which comprises an outer U-shaped section of strap metal, a complementary inner section of strap metal having a U-shaped central portion and laterally and oppositely extending clip-engaging means, said two sections defining a gum-shaped recess for receiving molten wax, and a strap member attached to said outer section with ends forming arcuate, spring-biased clips contacting said clipengaging means opposite the ends of said outer section.

PAUL GORDON CURREN.

REFERENCES CITED The following references are'of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,274,252 Eid July 31, 1918 684,253 Houston ,Oct, 8, 1901 1,083,163 Weaver et al Dec. 30, 1913 

